1. Field of the Invention
This invention is related to proximity detectors, and, more particularly, to metal proximity sensors.
2. Description of the Prior Art
A metal proximity sensor, of the type which relies upon the magnetic field generated by a sensing coil to detect the presence or passage of a metal object through the magnetic field is usually mounted on a metal plate or other similar type of support. The composition of the metal support, its bulk, and its resistivity can vary. Inasmuch as the magnetic field generated by the sensing coil can penetrate into the sensor's support, the applicant has discovered that the physical and electrical characteristics of the support can actually affect the operation and sensitivity of the sensor. Thus, for a metal proximity sensor having specific design and operating characteristics, exposure to various mounting plates or support structures can limit or interfere with the proper operation of the sensor. In fact, there may be times when the mounting plate may prevent proper operation of the sensor, since the mounting plate could absorb sufficient energy from the magnetic field to cause a continuous readout by the sensor which would erroneously indicate the presence of a metal object within close proximity of the sensing surface of the sensor.